Browsing by Author "Dillis, Sarah"

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    Antimony as a raw material in ancient metal and glass making: provenancing Georgian LBA metallic Sb by isotope analysis
    (Taylor & Francis, 2019-11-13) Dillis, Sarah; van Ham-Meert, Alicia; Leeming, Peter; Shortland, Andrew J.; Gobejishvili, Gela; Abramishvili, Mikheil; Degryse, Patrick
    Sb was frequently used as a raw material, both in ancient glass-making (as an opacifier and decolouriser) and metallurgy (either as an alloying element or as a pure metal). Despite this ubiquity, antimony production has only occasionally been studied and questions concerning its provenance are still not satisfactorily answered. This study evaluates the suitability of Sb isotope analysis for provenance determination purposes, as experiments under lab conditions have revealed fractionation occurring during redox processes in oxidising stibnites and in making opacified glasses. The results of this paper help to evaluate the possible influence of the pyrotechnological processes on the antimony isotope composition of glass artefacts. This paper focuses on the Caucasus as case study by applying mineralogical, geochemical and isotopic analysis to Georgian ores (mainly from the Racha-Lechkumi district) and Late Bronze Age (LBA; 15th–10th century BCE) metallic Sb objects found at the sites of Brili and Chalpiragorebi.
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    Isotopic evidence for the use of Caucasian antimony in Late Bronze Age glass making
    (Elsevier, 2020-06-29) Degryse, Patrick; Shortland, Andrew J.; Dillis, Sarah; van Ham-Meert, Alicia; Vanhaecke, Frank; Leeming, Peter
    Antimony (Sb) is considered a rare material in the archaeological record, found only in unusual circumstances. Nevertheless, antimony minerals were an important resource for several millennia, used in metallurgy and to opacify or decolour glass and glazes. In this way, Sb spread throughout the known world from the Chalcolithic onward. In glassmaking, stibnite was the only available resource that could provide in any measure the very pure Sb evident from trace element analyses of the earliest glass. Sb isotopic analysis has allowed Late Bronze Age Egyptian and Mesopotamian glass vessels and Caucasian Sb metallic beads to be compared to the possible ancient ore sources. The only known matches for the isotopic composition of the glass are stibnite ores from the Racha-Lechkumi district in the Caucasus (present-day Georgia), near the Zopkhito Au–Sb deposits, mined from the 17th century BCE. Conversely, the Sb metal beads represent several isotopic and trace element compositional groups, only one of which matches the Racha-Lechkumi stibnite. Sb extraction for glassmaking was likely unrelated to copper metallurgy, and may have been associated with the mining of precious metals.
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    A unique recipe for glass beads at Iron Age Sardis
    (Elsevier, 2019-06-28) van Ham-Meert, Alicia; Dillis, Sarah; Blomme, Annelore; Cahill, Nicholas; Claeys, Philippe; Elsen, Jan; Eremin, Katherine; Gerdes, Axel; Steuwe, Christian; Roeffaers, Maarten; Shortland, Andrew J.; Degryse, Patrick
    In large parts of the Mediterranean recipes for the earliest man-made glass changed from melting mixtures of crushed quartz pebbles and halophytic plant ashes in the Late Bronze Age to the use of quartz sands and mineral soda during the Early Iron Age. Not much is known about this transition and the experimental materials which would inevitably have been connected to such technological change. In this paper we present a unique snapshot of developments in glass technology in Anatolia during the Middle Iron Age, when glass is still a relatively rare commodity. The present work focusses on black glass beads decorated with yellow trails from eighth to seventh century BCE Sardis, glass beads that are very rare for this period, and on this site. A full elemental analysis of the beads was made, and Sr, Pb and B isotope ratios were determined. This study reveals the use of a combination of a previously unknown source of silica and of mineral soda, giving rise to elevated (granite-like) Sr isotope signatures, as well as high alumina and B concentrations. The yellow trails of glass on the beads consist of lead-tin yellow type II, lead stannate, showing the earliest occurrence of this type of opacifier/colourant so far, predating any other findings by at least four centuries. The production of these glass beads may be local to Sardis and experimental in nature. It is therefore suggested that Sardis may have played its role in the technological development of the glass craft during the Iron Age.